Glass containers are 100% recyclable and can be recycled endlessly without any loss in purity or quality. Over a ton of natural resources are saved for every ton of glass recycled. Energy costs drop about 2-3% for every 10% cullet (post-consumer glass) used in the manufacturing process. Glass furnace life is increased by 10% when recycled glass is used in the production of new glass containers. One ton of carbon dioxide is reduced for every six tons of recycled container glass used in the manufacturing process.
Although glass container manufacturers are able to use as much as 95% recycled glass in the manufacturing process, glass container manufacturers often use only about 35% recycled glass. When using recycled glass as feedstock to manufacture new glass containers, energy costs of glass container manufacturers can be 15% less, emissions can be reduced by 20%, and furnace life can be extended by 10%. Glass container manufacturers prefer to use all the recycled furnace-ready cullet they can procure. A significant barrier to this is the quality of recycled glass available and assurance that the cullet receive is furnace-ready cullet, which must be high purity clean and color-sorted. With contaminated cullet, the reject rate in the manufacture of new glass containers increases, which increases the cost of manufacturing new glass containers. Even one small contaminant in a manufactured bottle can result in rejection.
Consumers place their recyclables by their curb side, which is picked up by hauling companies and taken to a Material Recovery Facility (MRF) where the various recyclables are sorted out and the residual, which is a mixture having high glass content, is sent to Glass Processors to be cleaned, color sorted and then sold as cullet to glass container manufacturers for use in producing new glass containers.
In years past, consumers had to place recyclables in different bins by their curb side. However, in order to reduce the cost of recycling and increase the amount that is recycled, cities have since transitioned to “single stream collection” whereby all recyclables are placed in a single bin. With single stream collection, Material Recovery Facilities (MRFs) have to deal with co-mingled material. While MRFs remove larger pieces of paper, most of aluminum cans and plastic containers, their residue and what they are unable to remove, comes out of their facilities with a large percentage of broken glass, typically as three-color (clear, brown, green) mixed dirty glass. So glass is part of this residual that MRFs send to glass processors, hence the glass is mixed with a lot of other material which is considered to be contaminants. The glass processors receive this as their raw material feedstock, which can contain as much as 40 to 50% contaminant (non-glass). However, the furnace-ready cullet which glass processors are required to provide to glass container manufacturers must contain less than 0.001% contaminant or almost 100% clean color sorted glass. The quality of cullet is the most important factor for glass container manufacturers.
While producing quality cullet is important, the ability to test the cullet is crucial. Today glass processors use manual methods to test the quality of the cullet that is delivered to them. A material sample, usually 50 lbs, is spread on a work table, a quality inspection person manually separates the contents of the sample, weighs each content group, fills out a sheet of paper with data which is compared to the specification of the glass container manufacturer (or other end user) to determine if the cullet delivery passes or fails to meet specifications. This manual process can take up to 45 minutes for each sample. The samples have to be tested several times a day and for each truck shipment, adding high labor cost to the end product. Accordingly, there is a need for efficient and accurate method and system for testing the quality of cullet.